Has anyone had problems sometimes with the home or back button not responding at times? Kind of like a freeze where u have to press the buttons a couple of times then they will respond. Also, have you noticed that sometimes that pressing the power button will not wake the phone up? And when my phone call ends, it takes a while for the screen to come back from black so I can end the call. Should I get an exchange for my phone or are these issues supposed to be resolved with the update coming? Thanks